Supplementary coding on inductive debit cards and reading process

ABSTRACT

Supplementary coding on inductive debit cards and reading method by which information regarding variables, such as date of issue and country in which the card is valid, are included without any change in the number of credits on the card by using front and back handling strips normally provided on such cards. Such an encoding comprises the division of the strips, into a number of segments or tracks equal to the number of cell columns on the card, each track coinciding with the columns. Metalized tracks correspond to bit &#34;1 &#34; and non-metalized tracks to bit &#34;0 &#34;, the 4 tracks located at the corners of the card always being metalized. Reading of the information on the card is carried out during the insertion of the card into a reading head by a row of sensors farthest away from the entrance slot of the reading head. On detecting the presence of a pair of metalized tracks on the corners of the card, the bits contained in the handling strip are read and stored in a temporary register for later interpretation.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention concerns the improvement of disposable inductivedebit cards, such as the ones described in patent document BR 9201380-5and BR 9304503-4 and, specifically, to the insertion of supplementaryinformation on the cards, as well as to its reading using the existingreading devices as described in those patents.

2. Description of the Related Art

Inductive debit cards based on concepts originally contained in patentsBR 7804885, DE 2650959 and U.S. Pat. No. 4,029,945 are well known andare widely used as credit elements in public telephone systems. FIG. 1exemplifies the main features of a known card, akin to the one in FIG. 1of above mentioned document BR 9304503-4, containing a plurality ofcredit elements 12, arranged in 6 rows and 9 columns, totaling 50 usablecredits since four of the cells at corners 13, 14, 15 and 16 are used asindexing elements. The card also has blank strips 17 and 18, locatedbetween the central area and front end edge 19 and back edge 21, whichare made use of during insertion and withdrawal of the card from thereading head.

Even though the shown card is suitable for experimental use, or smallscale applications, the commercial use on a large scale basis requiresthe inclusion of additional information, such as, for instance, thefollowing:

Card validation date

Code of the country issuing the card

Manufacturers identification code

The inclusion of this information in central area 11 would necessarilyreduce the number of available credits on the card.

On the other hand, including the information on strips 17 and 18entails, as a drawback, the need to modify the reading head, since theexisting heads do not have sensors positioned at the strips. In view ofthe large number of telephone sets of this kind that are already inoperation, such a solution would require the expenditure of largeamounts of money, materials and labor, as all the installed readingheads would have to be replaced.

SUMMARY OF THE INVENTION

From the foregoing, the main objective of the present invention is theprovision of a way of including the supplementary information on cardswhile keeping the number of credits unchanged, and associating it with areading process of this information which uses the already existingreading heads, eliminating the need of any structural change to thelatter.

This and other objectives are achieved by the present invention byincluding metalized elements on the handling strips, having shapes anddimensions that allow for the reading of data on a card in motion.

According to another aspect of the present invention, the reading iscarried out during the time the strip is passing by the row of sensorsplaced farthest away from the card inserting slot.

According to still another aspect of the present invention, thesupplementary information is read off independently of card orientationin the reading head.

According to another aspect of the invention, the card is provided withindexing elements which allow for detectkion, during the insertion ofthe card into the reading head, of the existence of the metalizedelements while passing by the row of sensing coils that read off theinformation there contained.

BRIEF DESCRIPTION OF THE DRAWINGS

The previously mentioned characteristics, as well as other aspects andadvantages of the present invention, will become more evident from adetailed description of a preferred embodiment and of the attacheddrawing figures where:

FIG. 1 shows a known inductive debit card, such as described in documentBR 9304503-4.

FIG. 2 shows the placement of the information carrying elements in thehandling strips of an inductive debit card, according to the principlesof the present invention.

FIG. 3 shows an example of information coding, as well as the readingdirection of the information, according to the principles of the presentinvention.

FIGS. 4-a-4-c show the different positions of the card relative to thereading head, during the several stages of its insertion, according tothe principles of the present invention.

FIG. 5 shows, by means of a flowchart, the steps involved in the readingof supplementary information on a card, according to the principles ofthe present invention.

FIG. 6 shows an alternative way of achieving the aims of the presentinvention with an increase in the number of data items inserted into thehandling strips of a card.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in FIG. 2, the front handling strip 17 is divided, in thedirection of the card width, into as many segments or tracks 41, 42, . .. 49, as the cell columns on the card, the segments being aligned withthe axes 31, 32, . . . 39 of the columns. The rear handling strip 18 isdivided in the same way into segments 41', 42'. . . 49'.

According to the principles of the present invention, the four segments41, 49, 41', 49', located on the corners of the card, are alwaysmetalized; in the remaining segments, the presence or absence ofmetalization will correspond to the data bit--1 or 0,respectively--represented by each segment.

Still according to the principles of the present invention, the data bitsequences are identical on strips 17 and 18, which allows for thereading of the information independently of the card orientation duringinsertion into the reading head. Moreover, the use of the available bitswill depend on the number of variables one wishes to represent as wellas on the range of possible values of each variable.

FIG. 3 shows how two variables can be encoded on the card shown in FIG.2, such as, for example, the issue date and the country issuing thecard. From a total of 7 available bits, 4 bits from blocks 51 and 51'are made use of to encode the issue date of the card and 3 bits fromblock 52 and 52' to codify the country issuing the card. Considering,for example, that it is wished to encode the quarter in which the cardwas issued, then block 51 allows 2⁴ =16 quarterly issuing periods,equivalent to 4 years, while block 52 allows to encode 2³ =8 differentcountries. In the exemplary encoding of FIG. 3, tracks 42 and 44 have nometalization, and segments 43 and 45 are metalized; the reading of thecode, carried out in the direction 63 (left-hand border 61 to right-handborder 62 of the card) gives the binary coded number 0101, indicatingthat the card was issued on the 5th quarter counted from a standardreference date. In block 52, segments 46 and 47 are not metalized, whiletrack 48 is metalized, indicating the binary number 001, corresponding,for instance, to cards issued in Brazil. In this way, cards having adifferent code in block 52, as for example, 002, 003, etc., would berejected since these correspond to cards issued in other countries (forexample, 002=Uruguay, 003=Argentina, etc.). As previously mentioned, theencoding by metalizing segments of strip 18 would be identical to theone of strip 17, thus tracks 43', 35'and 48 are metalized while theremaining ones are not, since reading directions 63' and 63 are the samein both strips 17 and 18.

The designation of the side edges is set by convention. In this case,"left-hand" is considered to be edge 61 of the card, adjacent toopen-circuited indexing cells 13 and 16, "right-hand " edge 62 beingadjacent to the short-circuited cells 14 and 15.

For reading the supplementary data on a card, it makes no difference onwhich handling strip, 17 or 18, the reading is performed since bothcontain the same data. This detection employs the same principle usedfor the reading the credit cell condition, i.e., a metalized segmentwill draw power from the sensing coil circuit due to the induction, bymagnetic coupling, of a current on the metallic film. On the absence ofmetalization, this loss does not take place and the voltage between theterminals of the coil will be significantly larger, as taught on page13, lines 15 to 19 of patent document BR 9203968-5, among others.

As already mentioned, the existing reading heads comprise only sensorspositioned coincidently with the credit cells occupying central region11 of the card, thus making it necessary to perform the reading of thedata on the handling strips before the card has reached its finalposition within the reading head, that is, while the card is beinginserted into the reading head. According to the present invention, thereading is carried out by the row of sensing coils the farthest awayfrom the insertion slot, while the handling strip is passing by thosesensors. All that is necessary to carry out such a reading is to changethe software of the reading head, avoiding the need for any hardwaremodification in the reading head.

FIGS. 4-a-4-c illustrate several positions of the card along itsinsertion into the reading head, the corresponding reading processsequence being shown in FIG. 5.

Taking as the initial state of a telephone set, the one in which the setis not in use, the circuit keeps monitoring repeatedly sensors 65-66which have the function of detecting the presence of an inductive debitcard. FIG. 4-a shows the condition before the detection, in which card30 began to be inserted through front slot 69 of the reading head, nothaving yet reached sensor row 64, the farthest away from the slot. Inthis figure, the sensors are indicated only by their cylindrical ferritenuclei; as mentioned, sensor row 64 is responsible for the reading ofsupplementary data on the card.

FIG. 4-b shows the condition when the front edge 19 of the card has justpassed by row 64. In this figure, metalized tracks can be seen underboth verifying sensors at positions 65 and 66. On detecting thiscondition, which is equivalent to "both cells are short-circuited" or"both coils loaded" (steps 82 and 83 of FIG. 5), the reading of allsensors of the row 64 is triggered off, the resulting bits being storedin a temporary register for a later interpretation. Next, the readingprocess moves to step 84 in FIG. 5, monitoring the two sensor pairs65-66 and 67-68, i.e., checking the existence of both an open-circuitedcell and a short-circuited one in each of the pairs, step 85. Thissignals that the card has moved to the end of the insertion coursewithin the reading head, as is taught in document BR 9201380-5. At thismoment, it is possible to identify the position of the inserted card,that is, the "right-hand" border and the "left-hand" one since, in thecase shown, "left-hand" border 61 is adjacent to the open circuitedindexing cells 13 and 16 and the "right-hand" border is adjacent toshort-circuited cells 14 and 15.

Once this identification is completed, the circuit is able to read, inthe correct direction, the bits previously stored, step 87. If thisinformation corresponds to the one considered as valid (relative to theissuing date and issuing country), step 88, the card will be releasedfor use by carrying out the routine already known of counting theavailable credits and collecting them, according to the number calledand the duration of the call, step 89. In the case in which the dataresulting from the interpretation of the stored bits is not valid, thecard will be rejected, step 91.

FIG. 6 shows a second embodiment of the invention in which each handlingarea is sub-divided into two strips, allowing the quantity of bits thereencoded to be doubled. In this case, on strip 17 there will be a firstgroup of 7 bits, 42, 43 . . . 48, and a second group of 7 bits, 42a,43a. . . 48a, separated by a non-metalized strip 72, which, when passingby sensors 65-66, signals the exit of the first group from the readingarea and the entrance of the second group in the same reading area.Strip 18a is encoded akin to strip 18 so as to allow the reading ofsupplementary data independently from the position in which the card wasinserted into the reading head.

We claim:
 1. An inductive debit card comprising:a non-porous insulatingsubstrate having a front edge, a back edge, a left edge, and a rightedge to define a substantially rectangular shape having four corners; acentral area on one surface of the substrate having a plurality ofcredit cells formed of thin conductive metallic film and shaped asclosed rings arranged in rows parallel to said front and back edges andin columns parallel to said left and right edges; two blank handlingstrips located along a full width of the card between the central areaand the front edge and between the central area and the back edge of thecard, respectively, and supplementary coding for inclusion of additionalinformation while retaining the arrangement of credit cells in thecentral area of the card; wherein the additional information is coded inthe handling strips by the presence or absence of metalized tracks orsegments perpendicular to the front and back edges, each of saidmetalized tracks or segments being aligned with a credit cell column,the presence of a metalized track corresponding to an information bit"1" and the absence of a metalized track corresponding to an informationbit "0".
 2. The inductive debit card of claim 1, wherein the trackslocated on the four corners of the card are metalized.
 3. The inductivedebit card of claim 2 wherein each handling strip is divided into twoparts of substantially equal width, and separated by a blanknon-metalized strip parallel to the front edge and the back edge.
 4. Theinductive debit card of claim 1, wherein the additional information isidentical in both handling strips.
 5. The inductive debit card of claim4, wherein each handling strip is divided into two parts ofsubstantially equal width, and separated by a blank non-metalized stripparallel to the front edge and the back edge.
 6. The inductive debitcard of claim 1, wherein each handling strip is divided into two partsof substantially equal width, and separated by a blank non-metalizedstrip parallel to the front edge and the back edge.
 7. A method forreading supplementary coding on an inductive debit card comprising aflat non-porous insulating substrate having a front edge, a back edge, aleft edge, and a right edge to define a substantially rectangular shapehaving four corners, a central area on one surface of said substrate andhaving a plurality of credit cells formed of thin conductive metallicfilm shaped as closed rings, arranged in rows parallel to said front andback edges and in columns parallel to said left and right edges, and twoblank handling strips located along the full width of the card betweensaid central area and the front edge and between said central area andthe back edge card, respectively, said supplementary coding allowinginclusion of additional information in said handling strips includingthe presence or absence of metalized tracks or segments perpendicular tosaid front and back edges, each of said metalized tracks or segmentsbeing aligned with a credit cell column, the presence of a metalizedtrack corresponding to information bit "1" and the absence of ametalized track corresponding to information bit "0", said processcomprising the steps of:inserting said card into a reading head having acard insertion slot, through which the card slides into the readinghead, and including a plurality of sensors arranged in rows parallel tosaid card insertion slot and columns perpendicular to said cardinsertion slot, each sensor position being coincident with a credit cellposition when the card is fully inserted into said reading head, thefirst and last sensors in the rows located farthest and nearest to saidinsertion slot being card position verifying sensors; and detecting thepresence or absence of said metalized tracks by the sensor row locatedfarthest away from said insertion slot prior to full insertion of thecard into said reading head.
 8. The method of claim 7, wherein thedetecting step is triggered by the detection of the presence ofmetalized tracks by both card verifying sensors in the sensor rowlocated farthest away from the insertion slot when the card is not fullyinserted in said reading head.
 9. The method of claim 8, furthercomprising the steps of:storing information bits "1" corresponding tothe presence of metalized tracks and information bits "0" correspondingto the absence of metalized tracks in a temporary register; detectingcompletion of card insertion into the reading head by the card positionverifying sensors and identifying the left-hand edge and the right-handedge of the card fully inserted into the reading head; interpreting saidtemporarily stored bits; and rejecting or releasing the card for routineand normal credit accounting and collecting.